ISHS Acta Horticulturae 664: IV International Symposium on Irrigation of Horticultural Crops
EFFECT OF SALINITY ON EVAPOTRANSPIRATION AND YIELD OF SAN JOAQUIN VALLEY PISTACHIOS |
| Authors: | B.L. Sanden, L. Ferguson, H.C. Reyes, S.R. Grattan |
| Keywords: | irrigation, salinity tolerance, drainage, neutron probe, rootstock |
| Abstract:
A nine-year study was initiated in 1994 in a six year old pistachio orchard on the Westside of the San Joaquin Valley to test the salinity tolerance of four different pistachio rootstocks. The rootstocks were Pistacia atlantica, P. integerrima ‘Pioneer Gold 1’ (PG1) and ‘Pioneer Gold 2’ (PG2) and P. atlantica x P. integerrima ‘UCB1’. All were budded with a Pistacia vera ‘Kerman’ scion. Irrigation treatments ranged from 0.5 to 8 dS/m electrical conductivity (EC) with saline treatments simulating the quality of blended local drainage water. In 1996, the high salinity treatment was in-creased to 12 dS/m. After reaching stable rootzone salinities and orchard canopy cover of 60 to 80%, ET (as determined by soil water content depletion between irriga-tions) for the 4, 8 and 12 dS/m irrigation treatments for the 1999 and 2000 seasons was found to average 66, 53 and 46% of the control (0.5 dS/m) treatment, respec-tively. Despite this difference in soil water uptake there was no impact on yield up to 8 dS/m. Average yield for all rootstocks at the 12 dS/m level was 81% of the control yield. Only the 65% yield decline for UCB1 was statistically significant. For the last two years of the trial, a plastic barrier was installed to a depth of 1.5 m to eliminate the crossover of shallow roots from saline to non-saline plots. To further improve the precision of ET estimates, soil moisture monitoring was reduced to two rootstocks (PG1 and UCB1) to allow for an increase to four neutron-probe access tubes per tree installed to a depth of 1.8 m. ET was still significantly reduced by the 8 and 12 dS/m treatments to 78 and 63% of the control, respectively. Mean biennial nut yield de-clined significantly (R2>0.93) as a function of mean rootzone salinity greater than 10 dS/m for UCB1, Atlantica and PG2 rootstocks. The nut yield on the PG1 rootstock was unaffected up to the mean rootzone salinity (ECe) of 13.4 dS/m in the 12 dS/m treatment. | |
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